"We need some great failures," the muckraking journalist Lincoln Steffens wrote in his autobiography. "Especially we ever-successful Americans -- conscious, intelligent, illuminating failures." What Steffens meant was that a people confident in righteousness need occasionally to be reminded of their fallibility. The past 50 years have produced failures aplenty -- the Bay of Pigs, Vietnam and Iraq among them. Unfortunately, as Andrew Bacevich and John Dower demonstrate, the light of failure has not penetrated the darkness of delusion. As a result, wars provide a repeating rhythm of folly.

"Washington Rules" and "Cultures of War" are two excellent books made better by the coincidence of their publication. In complementary fashion, they provide a convincing critique of America's conduct of war since 1941. Steffens would have liked these books, specifically for the way they use past failures to explain the provenance of our current predicament.

Read "Cultures of War" first. It's not an easy book, but it is consistently perceptive. Dower examines Pearl Harbor, Hiroshima, Sept. 11 and the second Iraq War, drawing disconcerting linkages. Pearl Harbor and Iraq, he feels, demonstrate how otherwise intelligent leaders are drawn toward strategic imbecility. Both attacks were brilliantly executed in the short term, but neither paid sufficient attention to the long-term problem of winning a war. More controversially, Dower pairs Hiroshima with Sept. 11, both acts of terror born of moral certitude. Osama bin Laden and Harry Truman justified wanton killing with essentially the same Manichean rhetoric. Motives, context and scale might have been different; methods were not. For both leaders, the ability to separate good from evil made killing easy.

In 1941, Americans drew comfort from the stereotype of the irrational Oriental. They assumed that the Japanese would be easily defeated because they were illogical -- as their attack upon Pearl Harbor proved. That attack was indeed illogical (given the impossibility of defeating the United States in a protracted war), but it was not peculiarly Japanese. As Dower reveals, the wishful thinking, delusion and herd behavior within the court of Emperor Hirohito was a symptom of war, not ethnicity. The same deficiencies, in 2003, convinced those in the Oval Office that invading Iraq was a good idea.

Since the culture of war encourages patterned behavior, folly proliferates. This is the essence of the Washington rules that Bacevich elucidates. The rules dictate that protection of the American way of life necessitates a global military presence and a willingness to intervene anywhere. Power and violence are cleansed by virtue: Because America is "good," her actions are always benign. These rules have pushed the United States to a state of perpetual war. With enemies supposedly everywhere, the pursuit of security has become open-ended.

The alternative, according to Bacevich, is not isolationism or appeasement, two politically loaded words frequently used to pummel those who object to Washington's behavior. He advocates, instead, a more level-headed assessment of danger, advice all the more cogent since it comes from a former soldier. Iraq and Afghanistan did not threaten America; in fact, those countries and the world have become more dangerous because of heavy-handed American intervention. Nor does North Korea pose a threat. Nor did Vietnam.

One is reminded of John Winthrop, who, in 1630, told the future residents of Massachusetts Bay Colony: "We shall be as a City upon a Hill, the eyes of all people are upon us." Over subsequent decades, Winthrop's sermon became the American mission, fired by self-righteousness and fueled by self-confidence. From that mission emerged the idea of Manifest Destiny -- American ideals should spread across the continent and around the globe. Along the way, Americans lost sight of what Winthrop actually meant. His words were both inspiration and warning: Aspire to greatness, but remain honorable. Power lies in virtue. Winthrop envisaged a shining beacon, worthy of emulation. He saw no need to come down from the hill and ram ideals down the throats of the recalcitrant.

The power of virtue is Bacevich's most profound message. Instead of trying to fix Afghanistan's Helmand Province, he insists, Americans should fix Detroit and Cleveland. Instead of attempting to export notions of freedom and democracy to nations that lack experience of either, America should demonstrate, by her actions, that she is still a free, democratic and humane nation. Her real strength lies in her liberal tradition, not in her ability to kill.

Back in 1963, the Kennedy administration was faced with a steadily disintegrating situation in Vietnam. At a turbulent cabinet meeting, Attorney General Robert Kennedy asked: If the situation is so dire, why not withdraw? Arthur Schlesinger, present at the meeting, noted how "the question hovered for a moment, then died away." It was "a hopelessly alien thought in a field of unexplored assumptions and entrenched convictions." The Washington rules kept the United States on a steady course toward disaster.

Those unexplored assumptions and entrenched convictions have now pushed the United States into a new quagmire. Despite that predicament, both Dower and Bacevich try to end positively. "If change is to come, it must come from the people," argues Bacevich. Dower agrees. But these feeble attempts at optimism are the least convincing parts of two otherwise brilliant books. Barack Obama once promised that change was coming, but then quickly adhered to the old rules by escalating an unwinnable and certainly unaffordable war in Afghanistan. Failures, as Steffens hoped, have been illuminating, but after each flash of light, darkness has prevailed.

Gerard De Groot is a professor of history at the University of St. Andrews in Scotland and author of "The Bomb: A Life."